We are experiencing an increased rate of nova explosion observed from the northern hemisphere in the recent 2 years. Starting from July 2020 with the strongly reddened nova V1391 Cas, we are continuously observing some novae in outburst. Here, we report the observations of 5 classical novae: Nova Cas 2020 = V1391 Cas, Nova Per 2020 = V1112 Per, Nova Cas 2021 = V1405 Cas, Nova Her 2021 = V1674 Her and Nova Vul 2021 = V606 Vul. The best at the end - the recurrent symbiotic nova RS Oph. In this paper, we report our photometric and spectroscopic observations. Thorough analysis is to be done in the near future. At this moment we want to highlight two important facts. In the case of V1405 Cas, we know the orbital period of the progenitor. The progenitor of V1674 Her is an intermediate polar with known white dwarf spin period. In both cases, it will be very interesting to compare the values after the nova explosion. In the case of V1674 Her, we have already measured both the orbital and the spin period.

According to the current knowledge, classical novae outbursts are one of the most spectacular events performed by binary stars systems. The outburst is one consequence of the accretion of hydrogen-rich material onto a white dwarf in close binary systems. Such systems are generally called cataclysmic variables. So novae belongs to this type of variable stars. The optical brightness increase during the outburst is rapid and amplitude can reach 15 magnitudes. The following decline is slower and there is an empiric law establishing relationship between absolute maximum brightness and the rate of decline (MMRD). Of course the MMRD relationship was used as useful indicator of distance also for extragalactic objects. The typical value of the absolute maximum brightness is -7 magnitude. So classical nova can be easily observed even at the distance of the Galactic center. As a consequence, the distribution of observed novae on the sky shows strong concentration to the Galactic plane and the majority of novae are observed in directions towards the Galactic bulge. For observers on the northern hemisphere this preference represents a limitation. The Galactic center in Sagitarius constellation reach only low altitude above the horizon and the observing season is short. Fortunately, a statistical fluctuation occurred in 2020 and 2021. Six bright novae exploded in favorable positions for northern observers. This article reports the intense observing campaign performed by the authors.

Pavol A. Dubovský studied nuclear physics at the Comenius University, Bratislava (Slovakia). After 3 years he abandoned the university and started professional carrier in different positions in private companies and NGO‘s related to tourism and regional development. But at the same time he was an active amateur astronomer. At the beginning of the 21st century he became the most productive visual observer of variable stars in Slovakia ever. Since 2006 works at the Vihorlat Observatory as the main observer on the Astronomical Observatory on Kolonica Saddle. He manage different kind of observations – CCD photometry, spectroscopy and still also visual brightness estimates of variable stars. His research is focused mainly on cataclysmic variable stars. He is the author and co-author of more than 140 scientific papers published in reviewed journals.

J. ASB Soc., 2022, 3(1), 28-34

DOI: https://doi.org/10.51337/JASB20221206004

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